Phosphorescent coated sheet material



J. GOLDSTEIN 2,650,169 PHOSPHORESCENT COATED SHEET MATERIAL Aug. 25, 1953 Filed Sept. 28, 1949 INVENTOR.

Patented Aug. 25, I953 UNITED STATES PATENT OFFICE 2,650,169 PHOSPHORESOENT COATED SHEET MATERIAL Joseph Goldstein, Brooklinc, Application September 28, 1949, Serial No.

Mass.

6 Claims. (01. 11733.5)

application of such fabrics and plastics to slippers and shoes.

In my prior issued Patent No. 2,473,877, there nium dioxide or other suitable white pigment may be used. Upon this base coating is applied a ill with phosphorescent which will be pointed out The vehicles of all three coatings must of course be compatible with one another.

may be reactivated by exposure to black light,

or artificial light.

While phosphorescent pigments of the type used in the present invention actually continue to glow for a considerable number of hours, from ten to seventy-five hours, the decay is exponentially so that only a smaller portion of the time above stated provides actually visible luminescence.

Figure 1 shows the invention applied. to a pair of slippers.

Figure 2 shows a section taken through a portion of the inner sole along the line 2-2 of Figure 1, and

Figure 3 shows a set of curves relating to the combination of phosphorescent pigments used in the phosphorescent sheet.

As indicated in Figures 1 and 2, small sheets I and 2 in the form of a right and left inner-sole As has been previously set forth, the sheets have three coatings applied thereto, a base coat over which the phosphorescent coating is applied, and lastly the protective coating. The base coating should be a white primer in a paint or lacquer with which the other coats are compatible. A coating suitable for this purpose may be made of vinyl chloride-acetate resin dissolved in a suitable liquid, such as methyl-ethyl ketone in a concentration between 20% and 30 with suitable amounts of plasticizer, white reflecting pigments, such as titanium dioxide, filler, stabilizer with a small amount of stearic acid to deter settling and serve as a lubricant. A specific base coat formula on the basis of approximately onehundred pounds may comprise the following:

6040 lbs. vinyl chloride-acetate resins of a concentration of 20 to 30% in methyl-ethyl ketone 4-6 lbs. aryl alkyl-phosphate 4-6 lbs. plasticizer, such as di-Z-ethylhexyl phthalate.

13-17 lbs. white pigment which might be a combination of titanium dioxide and natural water ground calcium carbonate or other inert highly reflecting material nonsoluble in the vehicle 5-8 lbs. other materials such as suspensoids, wet

dispersed stabilizers, thinners, etc.

The formula above may of course be varied depending upon, the desired viscosity of the liquid audits uniformity.

The coating as applied should give a pure white sheen, providing a uniform reflecting surface with a minimum amount of light absorption. After this coat has been applied and left to dry, the phosphorescent coating may be applied. The base coat using one-hundred pounds as set forth above, will cover approximately one-hundred linear yards, 38 or 39 inches wide.

The phosphorescent coating should be approximately of the same thickness and should use the same vehicle for the phosphorescent pigment.

On the basis of approximately one hundred pounds, this may comprise:

6545 lbs. vinyl chloride-acetate resin solution 6-7lbs.plasticizer 2-2.5 lbs, titanium dioxide 3.5-2.5 lbs. aluminum stearate 18.8-19.3 lbs. phosphorescent pigment I This formula may be approximately varied over a 10% range but for best results the phosphorescent pigment used must be sufficient to provide a uniformly covered surface without voids of crystals. The aluminum stearate serves to prevent the settling of the heavier phosphorescent pigment in the coating, so that the phosphorescent pigment will remain uniformly throughout the coating as the coating dries and prevents the pigment from settling to the bottom of the coating,

in which case it would have to shine through the entire thickness of the coating. The top coating should be as clear as possible and serve only to provide a protective surface through which light would efficiently pass. This coating may also be of the same general thickness as the other two coats and comprise the following on the basis of one-hundred pounds:

8'? lbs. 20% vinyl chloride-acetate resins 13 lbs. A-lOO acryloid (40% solid), plus a very small amount of wet dispersed stabilizer, which amount may be compensated by decreasing the amount of vinyl chloride-acetate resin to make up the one-hundred pound formula It will be noted that in each of the three coatings, the basic substance of largest proportions is the vinyl chloride-acetate resin, which provides uniformity for all three coatings, thereby insuring uniform reflecting properties of light between successive layers of coatings. The formulas for each coating may also be made up of other resins, such as vinyl-acetate resins, cellulose nitrate and acetate resins, melamine resins, urea-formaldehyde resins and many others.

With regard to the phosphorescent pigments, I

a have determined by experiments, that by mixing phosphorescent pigments formed of calcium and strontium sulphides and strontium and calcium sulphides in certain definite proportions, particularly desirable phosphorescent pigments may be obtained, in that its after-glow intensity will be maintained above the ordinary visible limits for a substantially longer period of time than when one or the other pigments are used separately. This is shown in the curves of Figure 3, where A represents crystal pigment formed with Gas 15% and SrS and curve 13 represents crystal pigments formed with Gas 92% and SrS 8%. These percentages have fairly close tolerances but the material in curve A may be varied approximately l% and so also the materials of curve B.

In Figure 3, the abscissa axis is shown logarithmically as a time axis in logarithms to the base iii and phosphorescent intensity is shown as the ordinate in the ordinary scale.

Thestraight line 0 indicates an average minimum permissible intensity below which it is dinicult for the ordinary eye to see readily the phosphorescent material in the dark. When the intensity drops below this line, the phosphorescent material is not very efficient. The curve D shows a combination mixture of 50% of each of the pigments of A and B. This curve D, while it starts with no greater intensity than the curves A and B, nevertheless it maintains a higher intensity than the other two curves above the minimum line C for a longer period, after which it tends to diminish more rapidly. The result is that in combinations of approximately 50% of each of the pigments of A and B, a maximum desirable response is obtained providing a desired afterglow, which under ordinary conditions will endure for about 500 minutes. The phosphorescent coat therefore contains aproximately 50% of each of these pigments. Pigments of this type are manufactured commercially and readily obtaina e.

The coatings as produced by the present invention when used for slippers in the manner described will keep the slippers luminous by night, and need only be activated for less than a very few minutes, as for instance, at the time the individual is going to bed. If the slippers are exposed ratio of 8 and 92% respectively.

2. A sheet having a phosphorescent set forth in claim 1, in which the phosphorescent etone.

3. A sheet having a phosphorescent coating as set forth in claim 2, in which the synthetic resin is a vinyl chloride-acetate resin in approximately a 20% concentration in methyl-ethyl ketone.

5. A sheet having a phosphorescent coating applied to said sheet in a liquid state, said liquid comprising a composition as follows:

75 lbs. 20% to 30% solid content vinylchloride-acetate resin solution 6-7 lbs. plasticizer 2-2.5 lbs. titanium dioxide 3.5-2.5 lbs aluminum stearate 18.8-19.3 lbs. phosphorescent inorganic pigment crystals 6. A sheet as set forth in claim 5 in which the amounts may vary in a range of 10%.

JOSEPH GOLDSTEIN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,188,655 Hewitt June 27, 1916 1,291,739 Booth Jan. 21, 1919 1,321,024 Frank Nov. 4, 1919 1,349,396 Van Cliff Aug. 10, 1920 1,467,132 Bilstein Sept. 4, 1923 1,630,730 Daugherty May 31, 1927 2,039,734 Meder et al May 5, 1936 2,290,690 Lehman July 21, 1942 2,310,740 Leavy Feb. 9, 1943 2,341,009 Axelrad Feb. 8, 1944 2,413,459 Lynch Dec. 31, 1946 2,473,877 Goldstein June 21, 1949 2,498,592 Switzer Feb. 21, 1950 

1. A SHEET HAVING A PHOSPHORESENT COATING HAVING PHOSPHORESCENT CRYSTAL PIGMENTS COMPOSED OF SUBSTANTIALLY 50% CRYSTALS HAVING CALCIUM STRONTIUM SULPHIDES IN THE RATIO OF 15 AND 85 PERCENT RESPECTIVELY, AND 50% CRYSTALS HAVING STRONTIUM AND CALCIUM SULPHIDES IN THE RATIO OF 8 AND 92% RESPECTIVELY. 